The Delfino™ TMS320F2837xD is a powerful 32-bit floating-point microcontroller unit (MCU) designed for advanced closed-loop control applications such as industrial drives and servo motor control; solar inverters and converters; digital power; transportation; and power line communications. Complete development packages for digital power and industrial drives are available as part of the powerSUITE and DesignDRIVE initiatives. While the Delfino product line is not new to the TMS320C2000™ portfolio, the F2837xD supports a new dual-core C28x architecture that significantly boosts system performance. The integrated analog and control peripherals also let designers consolidate control architectures and eliminate multiprocessor use in high-end systems.

The dual real-time control subsystems are based on TI’s 32-bit C28x floating-point CPUs, which provide 200 MHz of signal processing performance in each core. The C28x CPUs are further boosted by the new TMU accelerator, which enables fast execution of algorithms with trigonometric operations common in transforms and torque loop calculations; and the VCU accelerator, which reduces the time for complex math operations common in encoded applications.

The F2837xD microcontroller family features two CLA real-time control coprocessors. The CLA is an independent 32-bit floating-point processor that runs at the same speed as the main CPU. The CLA responds to peripheral triggers and executes code concurrently with the main C28x CPU. This parallel processing capability can effectively double the computational performance of a real-time control system.

By using the CLA to service time-critical functions, the main C28x CPU is free to perform other tasks, such as communications and diagnostics. The dual C28x+CLA architecture enables intelligent partitioning between various system tasks. For example, one C28x+CLA core can be used to track speed and position, while the other C28x+CLA core can be used to control torque and current loops.

The TMS320F2837xD supports up to 1MB (512KW) of onboard flash memory with error correction code (ECC) and up to 204KB (102KW) of SRAM. Two 128-bit secure zones are also available on each CPU for code protection.

Performance analog and control peripherals are also integrated on the F2837xD MCU to further enable system consolidation. Four independent 16-bit ADCs provide precise and efficient management of multiple analog signals, which ultimately boosts system throughput. The new sigma-delta filter module (SDFM) works in conjunction with the sigma-delta modulator to enable isolated current shunt measurements. The Comparator Subsystem (CMPSS) with windowed comparators allows for protection of power stages when current limit conditions are exceeded or not met. Other analog and control peripherals include DACs, PWMs, eCAPs, eQEPs, and other peripherals.

Peripherals such as EMIFs, CAN modules (ISO 11898-1/CAN 2.0B-compliant), and a new uPP interface extend the connectivity of the F2837xD. The uPP interface is a new feature of the C2000™ MCUs and supports high-speed parallel connection to FPGAs or other processors with similar uPP interfaces. Lastly, a USB 2.0 port with MAC and PHY lets users easily add universal serial bus (USB) connectivity to their application.

This TI Design implements a digitally-controlled, 500-W, two-phase interleaved LLC resonant converter. The system is controlled by a single, C2000 microcontroller (MCU), MS320F28379, which also generates pulse width modulation (PWM) waveforms for all power electronic switching devices under all operating modes. This design implements an innovative current

sharing technique to accurately achieve current balancing between phases.

Resonant converters are popular DC-DC converters frequently used in server, telecom, automotive, industrial, and other power supply applications. The converters are a good choice for medium- to highpower applications because of their adherence to improving industry standards, ever-increasing powerdensity goals, and high-performance (efficiency, power density, and so forth) standards, These are variable-frequency converters where the PWM-switching frequency of operation frequently changes during runtime. For reliable operation the changing frequencies must not produce any glitches or irregular PWM behavior. For applications with high-output currents that require input-output isolation, it is a common practice to use synchronous rectification (SR) on the secondary of the isolation transformer. SR uses additional power electronic devices switching with changing frequencies. High-power applications may require use of multiphase interleaved converters. These interleaved converters have even more devices switching with variable frequencies and additionally require fixed-phase relationships between various phases under all operating frequencies. Guaranteeing correct PWM waveform generation with changing frequencies under all operating conditions is a big challenge for the controller. Furthermore, interleaving multiple phases of resonant converters presents current sharing challenges between phases.

Inadequate or improperly implemented current sharing or incorrect PWM waveform generation can lead to converter failure, significant system or component damage, and, in the worst case, significant property damage or resultant bodily injury or loss of life.

In server and telecom power supply applications, these converters are used to work as the isolated DCDC converter stage in the rectifier system. These converters provide high fficiency and power density through soft-switching, SR, and other techniques.

These converters are gaining popularity in automotive on-board charging applications. Additionally, these devices may be used as isolated, bi-directional converters in electric vehicles (EVs) and hybrid electric vehicle (HEVs).

This design implements a 500-W, two-phase, interleaved half-bridge (HB) LLC resonant converter with SR on the secondary. The system is controlled by a single C2000 MCU, TMS320F28379, which also generates correct PWM waveforms for all power electronic switching devices (MOSFETs) using the latest features on C2000 MCUs. An innovative current sharing technique is implemented by the C2000 MCU to accurately achieve current and phase balancing for multiphase interleaved converters.

The accompanying software allows programming the controller and experimenting with different control parameters to tune the control loop for good system performance. This design supports the use of C2000 powerSUITE tools like the compensation designer, the software frequency response analyzer, and the solution adapter. The software project allows users to evaluate the complete system with the help of these supported tools. This document provides the hardware and software design details along with the test results. This document also describes a structured step-by-step method to evaluate this solution by starting with a simple open-loop excitation and then working towards a complete well-tuned closed-loop system.